Cluster-shell competition in light nuclei-inclusion of non-central interactions in α-cluster model

The competition between the cluster and shell structure of light nuclei is discussed. First, we demonstrate in 12C by superimposing many Slater determinants that the cluster structure dissolute when the shell-model-like model space is introduced. The decrease of the energy from the 3α configuration by about 6 MeV is a clue to resolve a long-standing problem of the binding energies of 12C and 16O. As a next step, we propose a simple model to include the spin-orbit interaction (SMSO). By introducing only one parameter (Γ) to the wave function, describing an asymptotic transition of 12C from a 3α configuration to a 2α+4N configuration is represented, and we show a strong contribution of the spin-orbit interaction in the ground state. Furthermore, we propose a simplified model to directly take into account the contribution of the tensor interaction (SMT) for light nuclei by extending α-cluster model. The coupling effect of SMSO and SMT is shown to be important in 12C, contrary to 8Be